package util;

import java.io.*;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

/**
 * 
 * MultipartFormUtil类：处理多媒体表单工具类
 *
 */
public class MultipartFormUtil {
	// 上传配置
	private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3; // 3MB
	private static final int MAX_FILE_SIZE = 1024 * 1024 * 40; // 40MB
	private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB

	/**
	 * 
	 * @param request html请求
	 * @param response 账号 html响应
	 *
	 * @return List<FileItem> 多媒体表单
	 */
	public static List<FileItem> getFormItems(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// 检测是否为多媒体上传
		if (!ServletFileUpload.isMultipartContent(request)) {
			// 如果不是则停止
			PrintWriter writer = response.getWriter();
			writer.println("Error: 表单必须包含 enctype=multipart/form-data");
			writer.flush();
			return null;
		}

		// 配置上传参数
		DiskFileItemFactory factory = new DiskFileItemFactory();
		// 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
		factory.setSizeThreshold(MEMORY_THRESHOLD);
		// 设置临时存储目录
		factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

		ServletFileUpload upload = new ServletFileUpload(factory);

		// 设置最大文件上传值
		upload.setFileSizeMax(MAX_FILE_SIZE);

		// 设置最大请求值 (包含文件和表单数据)
		upload.setSizeMax(MAX_REQUEST_SIZE);

		// 中文处理
		upload.setHeaderEncoding("UTF-8");

		try {
			// 解析请求的内容提取文件数据
			List<FileItem> formItems = upload.parseRequest(request);

			if (formItems != null && formItems.size() > 0) {
				// 返回表单数据
				return formItems;
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}


	public static byte[] toByteArray(ByteArrayInputStream bais) throws IOException {
		ByteArrayOutputStream bos = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int length;
		while ((length = bais.read(buffer))!= -1) {
			bos.write(buffer, 0, length);
		}
		return bos.toByteArray();
	}

}
